A liquid crystal display device is used in various areas exploiting the advantages of being slim and lightweight, and low power consumption. A liquid crystal display panel (liquid crystal display element), used as a primary member in such a liquid crystal display device, generally has a constitution in which a liquid crystal material is sandwiched between a pair of glass substrates and a distance (cell gap) between two glass substrates is kept by a spacer.
Presently, as a spacer for liquid crystal display panels, spherical spacers mainly composed of plastic or an inorganic material are employed. And, as a method of locating such a spherical spacer on a substrate, a wet-spraying method of spraying a spacer dispersion liquid in the form of a liquid mist or a dry-spraying method of using an inert gas such as nitrogen or the like is generally employed. However, in these spraying methods, since the spacer is located on the substrate irregularly (in a random fashion), the spacer might be located in a displaying area and displaying characteristics might be adversely affect.
And so, various technologies of locating a spacer only in a non-displaying area are being investigated. As one of such technologies, for example, a technology of forming a resin spacer (the so-called photo spacer) by a photolithography process using a photosensitive resin material is proposed. According to this technology, a resin spacer can be selectively located at a desired position (in a non-displaying area) by prescribed exposure using a mask. However, the resin spacer formed by the photolithography process is inferior to a plastic spacer in point of cell thickness control so as to be uniform since it has larger variations in thickness than a plastic spacer. And, the resin spacer causes a production cost to increase significantly compared with the plastic spacer since this spacer uses a photolithography process.
On the other hand, various technologies of selectively locating a spherical spacer only in a non-displaying area are being investigated. For example, a method of removing the spacer located in a displaying area after spraying spacers throughout the surface of a substrate is proposed in Japanese Kokai Publication Hei-05-333346 and a method of printing a spacer in a non-displaying area using a printing method is proposed in Japanese Kokai Publication Hei-05-303102. However, there was a room for contrivance to improve in that in the former method, an additional step of removing the spacer in a displaying area is required. In the latter method, there is a possibility of adversely affecting the alignment of a liquid crystal because a screen for printing makes contact with an aligned displaying area.
Then, as a noncontact method of spraying the spherical spacers only in a non-displaying area, techniques of printing a spacer using an ink-jet (IJ) system are proposed in Japanese Kokai Publication Sho-57-58124, WO 97/36205, and Japanese Kokai Publication 2002-372717. However, it was very difficult to print a spacer evenly only in the non-displaying area in view of the ejection accuracy of an IJ system and widths of a black matrix (BM) and wires, which are non-displaying areas, and this is not described in the patent documents described above. On this problem, a method, in which the degradation of display characteristics resulting from running over of the spacer into a displaying area is inhibited by applying coloring treatment or alignment treatment to the surface of a spacer in advance taking running over of the spacer into a displaying area into account, is also contrived.
And, in recent years, display modes such as a Vertical Alignment (VA) mode and an In-Plane Switching (IPS) mode, which are a kind of liquid crystal display mode with a wide viewing angle, are widely employed other than a Twisted Nematic (TN) mode, generally used, as a liquid crystal display mode. In the VA mode, some rib-shaped projection structures for alignment regulation are provided not only within a pixel area but also in a non-displaying area. If there is such a rib-shaped projection structure and the like, a spacer dispersion droplet ejected by the IJ system and the like has a tendency to be evaporated along the rib-shaped projection structure, and therefore there is a possibility that the spacer is also located in the pixel area. Further, also in a TN mode and an IPS mode, it was difficult to locate all spacers in the non-displaying area due to the relationship between the ejection accuracy of an IJ system and the width of a non-displaying area as described above.
Thus, the difficulty of locating the spacer in the non-displaying area is going on increasing and the solution for this problem has been required.
[Patent Document 1]
Japanese Kokai Publication No. Hei-05-333346
[Patent Document 2]
Japanese Kokai Publication No. Hei-05-303102
[Patent Document 3]
Japanese Kokai Publication No. Sho-57-58124
[Patent Document 4]
WO 97/36205
[Patent Document 5]
Japanese Kokai Publication No. 2002-372717